2. 1) Introduction
2) Embryology and development
3 Components
4) Origin and Nuclei of facial nerve
5) Course and Branches
6) Ganglia associated with facial nerve
7) Blood supply
8) Examination of facial nerve
9) Age changes
10) Clinical relevance
11) Evaluation of nerve function
12) References
2
CONTENTS
3. 3
INTRODUCTION
Nervous System :
The bodily system that in vertebrates
is made up of the brain and spinal
cord, nerves, ganglia, and parts of the
receptor organs , that receives and
interprets stimuli and transmit
impulses to the effector organs.
4. 4
Cranial Nerves are 12 pairs of nerves
of the peripheral nervous system that
emerge from the foramina and fissures
of the cranium.
• All cranial nerves originate from
nuclei in the brain.
• All the nerves are distributed in
head and neck except the Vagus
nerve which also supplies the
structures of thorax & abdomen.
5. These nerves can be further divided into three groups
According to the type of fibres present :-
Pure sensory nerves – cranial nerves I, II, VIII.
Pure motor nerves – cranial nerves III,IV,VI, XI, XII.
Mixed nerves – cranial nerves V
,VII, IX, X .
5
6. Facial Nerve
The facial nerve is the seventh cranial nerve, it is a mixed nerve with motor
and sensory roots.
Emerges from the brain stem between the pons and medulla, controls muscles of
facial expression, and muscles of the scalp and ear, as well as buccinator,
platysma, stapedius, stylohyoid, and posterior belly of digastric.
Carries parasympathetic secretory fibers to submandibular and sublingual
salivary glands , lacrimal gland and to mucous membranes of oral and nasal
cavities.
6
7. 7
Conveys enteroceptive sensation
from eardrum and external
auditory canal, proprioceptive
sensation from muscles it
supplies, and general visceral
sensation from Salivary glands
and mucosa of nose and pharynx.
8. EMBRYOLOGY AND DEVELOPMENT
◉ The Facial nerve is developmentally derived from the
hyoid arch, which is the second branchial arch.
◉ It arises as 2 main divisions- motor and sensory:
The motor division of facial nerve is derived from the
basal plate of the embryonic pons.
The sensory division originates from the cranial neural
crest.
8
9. Facial nerve course, branching pattern, and
anatomical relationships are established during
the first three months of prenatal life.
The first identifiable Facial Nerve tissue is
seen at the third week of gestation :
facioacoustic primordium or crest.
9
10. FACIAL NERVE EMBRYOLOGY 4th WEEK
By the end of the 4th week,
the facial and acoustic
portions are more distinct.
The facial portion extends
to placode.
The acoustic portion
terminates on otocyst.
10
11. FACIAL NERVE EMBRYOLOGY 5th to 6th WEEK
◉ Early 5th week, the geniculate ganglion forms from distal
part of primordium.
◉ It separates into 2 branches: main trunk of facial nerve and
chorda tympani.
◉ At the beginning of the fifth week Nervus intermedius
develop. It might not be visible as a separate nerve until
approximately the 7th week.
11
12. 7th WEEK
◉ Early 7th week, geniculate ganglion is well-
defined and facial nerve roots are recognizable.
◉ By the middle of this week, the trunk of the facial
nerve, which is already formed, bifurcates into
the temporo-facial and cervicofacial branches.
◉ Around the end of this week different fascicles
that originate from these branches are recognized
clearly.
12
a
13. The peripheral segment of the facial nerve undergoes extensive
branching from Week 10 to 15.
The temporal, zygomatic, oral, mandibular and cervical regions will
give origin to the five main (terminal) branches of the facialnerve.
Towards the end of pregnancy, the tympanic bone and the mastoid
process are not fully developed, so the petrous portion of the facial
nerve does not exist and will not be formed until between 2 and 4
years of age.
The nerve is not fully developed until about 4 years of age.
13
15. 1. General sensory fibres : These fibres are responsible for
transmitting signals to the brain from the external acoustic meatus,
as well as the skin over the mastoid and lateral pinna.
2. Special sensory fibres: These are responsible for receiving and
transmitting taste information from the palate and anterior two-
thirds of the tongue.
16. 3. Visceral/autonomic motor fibres: in the facial nerve are
responsible for innervating: the lacrimal gland, submandibular
gland, sublingual gland, and the mucous membranes of the nasal
cavity and hard and soft palate allowing for production of tears,
saliva, etc. from these locations.
4. Somatic motor fibres : These are responsible for innervating the
muscles of facial expression and muscles in the scalp (which are
derived from the second pharyngeal arch), as well as the stapedius
muscle in the ear, the posterior belly of the digastric muscle, and the
stylohyoid muscle.
17. Origin
The facial nerve is attached to the brainstem by two roots:
◉ Large motor root
◉ Smaller sensory root.
These two roots of the facial nerve are attached to the lateral part of the
lower border of the Pons just medial to the eighth cranial nerve.
18. 18
The sensory root is attached midway between the motor root (medially) and
the vestibulocochlear nerve (laterally), so known as the Nervus intermedius or
Nerve of Wrisberg.
The motor root is located medial to the sensory root.
19. NUCLEI OF FACIAL NERVE
19
1. Motor Nucleus of Facial
Nerve
• It lies in the lower part of pons .
• The fibres supplying the muscles of
second branchial arch originate from
here.
2. Superior Salivatory Nucleus • It lies in the pons , lateral to the motor
nucleus.
• It provides preganglionic parasympathetic
secretomotor fibres to submandibular and
sublingual salivary glands.
The fibres of the nerve are connected to four nuclei situated in the lower Pons.
20. 20
3. Nucleus of Tractus
Solitarius
• It receives the taste sensation from
the anterior 2/3 of the tongue via
the central processes of the cells of
the geniculate ganglion of the facial
nerve.
• It also receives afferent fibres from
the glands.
4. Spinal Nucleus of
Trigeminal Nerve
• Distribution: Part of skin of external
ear.
• Function: Exteroceptive (superficial)
sensation in skin and mucous
membrane
22. COURSE OF FACIAL NERVE
22
Anatomically, the course of the facial
nerve can be divided into two parts:
Intracranial – the course of the
nerve through the cranial cavity, and
the cranium itself.
Extracranial – the course of the
nerve outside the cranium, through
the face and neck.
23. Intracranial Course of Facial
Nerve
The nerve arises in the pons in
brainstem. It begins as two roots; a
large motor root, and a
small sensory root (Nervus
intermedius).
The two roots travel through the
internal acoustic meatus (a 1cm
long opening in the petrous part of
temporal bone) and enter into the
facial canal.
23
24. 24
Three important events occur :
The 2 roots fuse to form facial nerve.
The nerve forms the geniculate ganglion.
The nerve gives rise to the greater petrosal
nerve (parasympathetic fibres to mucous and
lacrimal glands), the nerve
to stapedius (motor fibres to stapedius
muscle), and the chorda tympani (special
sensory fibres to the anterior 2/3 tongue and
parasympathetic fibres to submandibular and
sublingual glands).
25. 25
The facial nerve then exits the facial canal (and the cranium)
via the stylomastoid foramen, located just posterior to the
styloid process of the temporal bone.
26. 26
After exiting the skull, the facial nerve
turns superiorly to run just anterior to the
outer ear.
The first extracranial branch to arise
is the posterior auricular nerve. It
provides motor innervation to the some of
the muscles around the ear.
Immediately distal to this, motor branches
are sent to the posterior belly of
the digastric muscle and to
the stylohyoid muscle.
Extracranial Course of Facial Nerve
27. 27
The main trunk of the nerve, now termed the motor root of the
facial nerve, continues anteriorly and inferiorly into the Parotid
gland.
Within the parotid gland, the nerve terminates by splitting into
five branches:
1. Temporal branch
2. Zygomatic branch
3. Buccal branch
4. Marginal mandibular branch
5. Cervical branch
These branches are responsible for innervating the muscles of
facial expression.
29. 1. Greater Petrosal Nerve :
• It arises from the genu of facial nerve
within the facial canal.
• The nerve passes anteriorly & medially
through bone & exits through the
superior hiatus on the anterior slope of
petrous temporal ridge in the middle
cranial fossa.
Intracranial Branches
30. 30
Here it heads towards the foramen lacerum, drops partially and then enters the
pterygoid canal.
• At this point, it joins with deep petrosal nerve to form nerve to pterygoid
canal (Vidian Nerve).
• It travels through the canal & joins pterygopalatine ganglion .
• The nerve conveys preganglionic secretomotor fibres to lacrimal gland
& nasalmucosa.
31. 31
2) Nerve to stapedius :
• The nerve to stapedius muscle arises from the facial
nerve as it passes downward in the posterior wall of
the tympani.
• It reaches the muscle through a minute opening in the
base of the pyramid.
• The stapedius muscle contracts in response to loud
noises, preventing excessive oscillation of the stapes,
thereby dampening its vibrations and controlling the
amplitude of sound waves. In paralysis of the muscle ,
even normal sounds appear too loud and is known as
HYPERACUSIS.
32. 32
3) Chorda Tympani :
• Arises in the vertical part of the facial canal
about 6mm above the stylomastoid foramen.
• It runs upwards and forwards in a bony
canal.
• It enters the middle ear and runs forwards in
close relation to the tympanic membrane.
• It leaves the middle ear by passing through
the petrotympanic fissure.
33. 33
• It then passes medial to the spine of the sphenoid and enters the
infratemporal fossa.
• Here, it joins the lingual nerve through which it is distributed. It carries:
a) Preganglionic secretomotor fibres to the submandibular ganglion for
supply of the submandibular and sublingual salivary glands.
b) Taste fibers from the anterior two-thirds of the tongue except
circumvallate papillae.
34. Extracranial Branches
1. Posterior auricular nerve:
“ It supplies the auricularis posterior
and the occipitalis and intrinsic
muscles on the back of auricle.”
2. Digastric branch:
“Supplies the posterior belly of
digastric muscle.”
3. Stylohyoid branch :
“Styohyoid muscle.”
34
36. 36
Crosses the zygomatic arch and supply :
a. Auricularis anterior
b. Auricularis superior
c. Intrinsic muscles on the lateral side of
the ear
d. Frontalis
e. Orbicularis oculi
f. Corrugator supercilii
1. Temporal Branch :
37. 37
II. Zygomatic Branches:
• Run across the zygomatic bone and supply the orbicularis oculi.
III. The buccal branches: are two in number
• The upper buccal branch runs above the parotid duct and the lower
buccal branch below the duct.
• They supply muscles in that vicinity especially the buccinator.
38. 38
IV. The marginal mandibular branch:
• Runs below the angle of the mandible deep to platysma.
• It crosses the body of the mandible and supplies muscles of the
lower lip and chin.
V. The cervical branch:
• Emerges from the apex of the parotid gland.
• It runs downward and forwards in the neck to supply the platysma.
39. GANGLIAASSOCIATED WITH THE FACIAL
NERVE
Geniculate ganglion
Submandibular
ganglion
Pterygopalatine
ganglion
39
40. Geniculate ganglion
Is located on the first bend of
the facial nerve, in relation to
the medial wall of the middle
ear.
It is sensory ganglion.
The taste fibres present in the
nerve are peripheral processes
of pseudounipolar neurons
present in the geniculate
ganglion.
40
41. Submandibular ganglion
The submandibular ganglion is
small and fusiform in shape.
It is situated above the deep
portion of the submandibular
gland, on the hyoglossus muscle,
near the posterior border of the
mylohyoid muscle.
41
42. 42
It is parasympathetic ganglion
for relay of secretomotor fibres
to the submandibular and
sublingual glands.
It receives a branch from the
chorda tympani nerve which
runs in the sheath of the
lingualnerve.
43. 43
The pterygopalatine ganglion (meckel's
ganglion, nasal ganglion or sphenopalatine
ganglion) is aparasympathetic ganglion found
in the pterygopalatine fossa.
It's largely innervated by greater petrosal
nerve; and its axons project to the
lacrimal glands and nasal mucosa.
Pterygopalatine ganglion
44. 44
The facial nerve gets its blood
supply from:
a) Anterior inferior cerebellar
artery – at the
cerebellopontine angle.
b) Labyrinthine artery (branch
of anterior inferior cerebellar
artery) – within internal acoustic
meatus.
BLOOD SUPPLY
45. 45
c) Petrosal branch of middle meningeal artery –
geniculate ganglion and nearby parts.
d) Stylomastoid artery (branch of posterior auricular
artery) – mastoid segment.
e) Posterior auricular artery supplies the facial
nerve at & distal to stylomastoid foramen.
46. 46
Testing the temporal branches of the
facial nerve :
To test the function of the temporal
branches of the facial nerve, a patient is
asked to frown and wrinkle his or her
forehead.
Testing the Zygomatic branches of
the facial nerve :
The patient is asked to close their eyes
tightly.
Testing of Facial Nerve Branches
47. 47
Testing the buccal branches of
the facial nerve :
• Smile and show teeth
(orbicularis oris).
• Puff up cheeks (buccinator).
• Tap with finger over each cheek
to detect ease of air expulsion.
50. LESIONS OF FACIAL NERVE
The facial nerve has a wide range of functions. Thus, damage to the nerve
can produce a varied set of symptoms, depending on the site of the lesions.
50
LESIONS CLINICAL FEATURES
A) AT THE STYLOMASTOID FORAMEN FACIAL PALSY
B) ABOVE CHORDA TYMPANI FACIAL PALSY, SALIVATION, LOSS OF TASTE FROM ANT.
2/3RD OF TONGUE.
C) ABOVE NERVE TO STAPEDIUS B, LOSS OF STAPEDIAL REFLEX.
D) AT EXTERNAL GENU C , LOSS OF LACRIMATION
52. FACIAL PALSY
Facial palsy refers to weakness of the facial muscles,
mainly resulting from temporary or permanent
damage to the facial nerve.
When a facial nerve is either non-functioning or
missing, the muscles in the face do not receive the
necessary signals in order to function properly.
52
57. BELL’S PALSY
It is defined as an idiopathic paresis of the facial
nerve of sudden onset.
Bell's palsy is named after Sir Charles Bell, who
has long been considered to be the first to describe
idiopathic facial paralysis in the early 19th century.
However, it was discovered that Nicolaus Anton
Friedreich (1761-1836) and James Douglas
(1675-1742) preceded him in the 18th century.
57
58. DEMOGRAPHICS OF BELLS PALSY
60 %- 75 % of facial palsy is Bell’s type.
Any age group may be affected though incidence rises
with increasing age. A positive family history is present
in 6–8% of patients.
Recurrence is seen in 7 to 12% of patients; however,
recurrence should heighten suspicion for another etiology,
such as a tumour involving the facial nerve.
58
59. Risk of Bell’s palsy is high in diabetic
patients (with microvascular angiopathy)
and in pregnant women in 3rd trimester
(retention of fluid leading to oedema or
compression within Fallopian canal).
59
60. Clinical Features
Unilateral involvement
Inability to smile, close eye or raise
eyebrow
Whistling impossible
Drooping of corner of the mouth
Inability to close eyelid (Bell’s sign)
60
61. Inability to wrinkle forehead
Loss of blinking reflex
Slurred speech
Mask like appearance of face
Loss/ alteration of taste
61
62. Diagnosis
Bell’s Palsy is a diagnosis of exclusion – diagnosed by elimination of other reasonable
possibilities.
Minimum diagnostic criteria for labelling bell’s palsy:
Paralysis or paresis of all muscle groups on one side of the face.
Sudden onset.
Absence of signs of central nervous system disease.
Absence of signs of ear disease.
Rule out all other known causes of peripheral facial paralysis.
62
63. Treatment
General management -
Reassurance and psychological support.
Eye care :
Protection of the eye is the most urgent consideration in facial palsy. Due to incomplete
closure of eye, tear film from the cornea evaporates causing dryness, exposure keratitis
and corneal ulcer.
Frequent use of eye drops frequently during the daytime, whilst at night, eye should be
taped closed after putting thicker ointments containing petroleum, mineral oil.
63
64. Use of large-lens sunglasses.
Patients having long-term facial nerve
palsy are advised to close their eye
manually using a finger as well as
attempting to stretch the upper lid in
order to prevent shortening caused by
unopposed action of levator palpebrae
superioris muscle.
Corneal protection with lubrication
and patching.
64
65. Medical management :-
Commonly used medications to treat Bell's palsy include:
Steroids: Prednisolone is the drug of choice. If patient reports within 1
week, the adult dose of prednisolone is 1 mg/kg/day divided into
morning and evening doses for 5 days. The patient is called for follow-
up on the fifth day. If paralysis is incomplete or is recovering, dose is
tapered during the next 5 days. If paralysis remains complete, the same
dose is continued for another 10 days and thereafter tapered in next 5
days .
65
66. Antiviral drugs :
The role of antivirals remains unsettled. Antivirals alone have shown no benefit
compared with placebo. Antivirals added to steroids are possibly beneficial for
some people with Bell's palsy.
Steroids can be combined with Acyclovir.
The usual recommended oral regime is prednisone 1mg/kg/day for 10 days
and oral acyclovir (400mg five times daily) for 10 days or valacyclovir (500
mg, three times a day).
66
67. Physical Therapy
Re-coordinating the facial
muscles through retraining is an
important step to be followed
during the treatment strategical
phenomena of Bell’s palsy to
stop the unwanted movements
experienced. Exercises for
Bell’s palsy slowly create the
brain-to-nerve-to-muscle
routine bringing back the
original movement orders and
arrangements.
67
68. Surgery
Facial nerve decompression of vertical and tympanic segments or whole
of the fallopian canal. It improves the micro-circulation and relieve
pressure of the nerve.
Facial nerve injury and permanent hearing loss are possible risks
associated with this surgery.
68
69. Rarely, plastic surgery may be needed to correct lasting facial nerve
problems.
Facial reanimation helps to make the face look more even and may
restore facial movement.
Examples of this type of surgery include eyebrow lift, eyelid lift, facial
implants and nerve grafts. Some procedures, such as an eyebrow lift,
may need to be repeated after several years.
69
70. RAMSAY HUNT SYNDROME/HERPES ZOSTER OTICUS
It is an acute peripheral facial neuropathy
associated with a typical erythematous
vesicular rash of the skin of the ear canal,
auricle or mucous membrane of
oropharynx.
It is caused by the re-activation of the
latent Varicella Zoster virus in the
geniculate ganglion.
The syndrome is more common in old age
> 60 years.
70
71. Complications:
• Post herpetic neuralgia.
• Eye damage (blurred vision) may occur.
• Hearing loss & facial weakness may be
permanent.
71
72. COMPARISON B/W RAMSAY HUNT
SYNDROME AND BELL'S PALSY
Bell's palsy also is a result of injury to the facial nerve
however there is no red rash associated with Bell's palsy as
there is with Ramsay Hunt syndrome.
Ramsay Hunt syndrome is caused by the Varicella virus that
also causes chickenpox whereas Bell’s palsy is idiopathic.
Ramsay Hunt syndrome is commonly more painful than
Bell's palsy.
Both can cause eyelid and mouth paralysis on one side of the
face.
72
73. LYME DISEASE
It is a vector-borne (spirochete
Borrelia burgdorferi), multisystem
inflammatory disease involving
skin, nervous system, heart and
joints.
Transmitted to humans by the bite
of ticks.
73
74. Clinical features: -
Acute facial nerve palsy, which is usually unilateral but can be bilateral
especially in children, recovers within few weeks to months.
Flu-like symptoms
Erythema migrans.
Treatment :-
Doxycycline or amoxicillin for 14–21 days in patients having facial nerve
palsy.
74
75. TRAUMATIC FACIAL PARALYSIS
Fractures of Temporal Bone :
Temporal bone is very thick and hard structure located in the base
of the skull. Skull base has multiple foramina, increasing
susceptibility to traumatic injury.
Temporal bone contains important structures like facial nerve,
labyrinth, CN VIII, ossicles, carotid artery, jugular vein etc. Any
or all structures can get involve in fractures of temporal bone.
75
76. • Motor vehicle accident
• Fall from height
• Physical assaults
• Gunshot wound
• Any trauma causing head,
maxillofacial and spine
injuries.
76
Etiology:
77. IATROGENIC INJURY TO FACIAL NERVE
Ear or Mastoid Surgery
Facial nerve can get injured during middle ear or mastoid surgery. The
most common site of injury during middle ear or mastoid surgery is the
distal tympanic segment including the second genu, followed by the
mastoid segment.
The incidence of facial nerve palsy has been reported to be between
0.6% and 3.6%.
77
78. Treatment
:
Exploration with decompression of proximal and distal segments of the nerve
should be undertaken.
Facial palsy in seen immediately after surgery and if the nerve was identified or
was not at risk during the operation, a few hours of observation will usually
allow for any local anaesthetic-induced weakness to clear.
The possibility of a tight mastoid dressing over an exposed nerve should also be
considered and it is wise to remove the pack. If the paralysis is incomplete, the
patient should be started on oral steroids and observed clinically.
In cases of progression to full paralysis, exploration should be considered.
78
79. Parotid Gland Surgery and Anaesthesia
Facial nerve can get injured in parotid
surgery or sometimes it is deliberately
excised in malignant tumours.
After parotid surgery, around 50% develop
temporary facial weakness while 7% end
up with permanent facial palsy.
Use of facial nerve monitor during parotid
surgery helps in avoiding injury to facial
nerve and at the end of the surgery the
main trunk should be stimulated to confirm
continuity.
79
80. CERVICOFACIAL RHYTIDECTOMY ("Facelift")
Cervicofacial rhytidectomy may be performed in the subcutaneous plane, the
deep plane, the subperiosteal plane, and the sub-superficial
musculoaponeurotic system (SMAS) plane.
Facial nerve branches run below the SMAS plane. The deep plane technique
(which necessitates the release of facial ligaments), tissue repositioning and
surgical dissection as performed using the deep plane facelift carries the highest
risk of damage to branches of the facial nerve.
80
81. The commonest branch of the facial nerve that can suffer an injury during a
facelift is the buccal branch.
Damage to the buccal branch is typically asymptomatic and, when seen, may
show recovery over several months.
81
82. Facial nerve injury in New Borns
As the mastoid process is rudimentary (not completely developed) at
birth, the facial nerve is more easily damaged in new borns.
Birth injuries or other trauma, can therefore cause an ipsilateral facial
palsy.
This is serious since buccinator is supplied by facial nerve and is
necessary for sucking (feeding).
82
83. Nervous twitch :
It is also known as facial tic, habit spasm of face.
It occurs in childhood & is characterized by repetitive facial
movements that are reproducible & can be prohibited on
command.
Treatment may be as simple as reassurance or may require
aggressive drug therapy.
83
85. Schirmer’s
Test :
Geniculate ganglion and petrosal nerve
function test.
Schirmer’s test is +ve when :
Affected side shows less than half the
amount of lacrimation seen on normal
side.
Sum of lengths of wetted filter paper for
both eyes is less than 25mm.
85
86. Stapedius
reflex :
Nerve to stapedius muscle test.
Impedence auditometry is used. It records the presence or absence of stapedius
muscle contraction to sound stimuli – 70 to 100 db above hearing threshold.
If there is a lesion proximal to stapedius nerve , an absence reflex or a reflex less
than half the amplitude is observed.
86
87. CONCLUSION
The facial nerve plays a key role in making facial expressions. It controls facial
muscles that help to smile, frown, scrunch up the nose and wrinkle forehead.
This nerve also helps with movements like blinking and sensations like tasting.
Health conditions, injuries and surgeries can affect the facial nerves. If one
experiences temporary or permanent facial nerve weakness or paralysis –
immediate consultation from health care professional should be taken. Facial
nerve palsy is the most devastating neurological complication and therefore, a
surgeon should always try to avoid the nerve injury during surgery. It has a
negative impact on the patient’s quality of life, apart from the serious
medicolegal issues for the operating surgeon.
87
88. REFERENCES
BD Chaurasia Head and neck, brain Volume 3, Fifth edition.
Head and neck Anatomy For Dental Medicine, Eric W.Baker.
Dr. Rahul Bagla Online ENT Textbook >> Facial Nerve
Paralysis.
Gray’s Anatomy, Third edition, Richard L. Drake.
Gray’s Clinical Neuroanatomy, Elliot L. Mancall.
88
Enteroceptive : Light touch, pain and temperature. Proprioceptive : Body’s ability to sense movement, action
DM – progressive muscle wasting and weakness. Type I includes muscle away from center (like legs,arms), type II includes muscles close to center neck shoulder
Infranuclear part receives only crossed fibres from one hemisphere .
Contraindications to use of steroids include pregnancy, diabetes, hypertension, peptic ulcer, pulmonary tuberculosis and glaucoma
Bacterial is transmitted to human by infected deer ticks.
Erythema migrans is a circular red area that sometimes clears in the middle , forming a bull’s eye pattern. Can spread upto 12 inches. Usually 2 to 2.5 inches.
